C

Cancel Async Task if not Completed after a Max Time

See more Async Examples

Demonstrates how to wait a maximum amount of time for an asynchronous task to completed. If not completed in the allotted amount of time, the task is cancelled. C

#include <C_CkHttp.h>
#include <C_CkTask.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkHttp http;
    int waitMaxMs;
    const char *downloadUrl;
    HCkTask task;
    BOOL wasCanceled;

    success = FALSE;

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    http = CkHttp_Create();

    //  Set some timeouts, in seconds:
    CkHttp_putConnectTimeout(http,15);
    CkHttp_putReadTimeout(http,15);

    //  Wait a max time of 2 seconds for the task.
    //  In this example, it's an unreasonably small amount of time,
    //  which means the task will get cancelled.
    waitMaxMs = 2000;

    //  We're just going to download for 2 seconds and then cancel.
    //  Substitute your own URL with a large enough file for testing..
    downloadUrl = "http://download.mono-project.com/archive/4.6.1/windows-installer/mono-4.6.1.5-gtksharp-2.12.38-win32-0.msi";

    task = CkHttp_DownloadAsync(http,downloadUrl,"qa_output/mono.msi");
    CkTask_Run(task);

    //  Wait a maximum of waitMaxMs for the task (i.e. the HTTP download) to complete.
    //  The Wait method returns when the task has been canceled, aborted, or completed, or when the max allotted time has passed.
    CkTask_Wait(task,waitMaxMs);

    //  At this point, the download may or may not have completed.  
    //  Rather than checking the Task status, we can call task.Cancel because
    //  if the Task is no longer running (because it already completed, was canceled or aborted), then the 
    //  call to Cancel is a NO-OP (meaning it does nothing and the Task's status is unaffected).
    //  Also, task.Cancel returns TRUE if the task was in the "queued" or "running" state and was canceled or aborted. 
    //  The method returns FALSE if the task has any other status.
    wasCanceled = CkTask_Cancel(task);
    if (wasCanceled == TRUE) {
        printf("The HTTP download took too long and was canceled.\n");
    }
    else {
        //  Find out what happened.
        if (CkTask_getStatusInt(task) == 7) {
            //  The task completed, which means the background thread's call to Download completed
            //  with success or failure.  Find out which...
            success = CkTask_GetResultBool(task);
            if (success == TRUE) {
                printf("Download successful!\n");
            }
            else {
                printf("Download failed prior to waitMaxMs...\n");
                printf("%s\n",CkTask_resultErrorText(task));
            }

        }
        else {
            //  The task must've been canceled or aborted by some other means..
            printf("Task did not complete.  Final status: %s\n",CkTask_status(task));
        }

    }

    CkTask_Dispose(task);


    CkHttp_Dispose(http);

    }